I should start by saying that I don’t know Justin Bieber. Never met the kid, never seen him perform, don’t really know his music that well.

But if even I have heard stories about the teenage sensation’s alleged flirtation (or full-fledged infatuation) with marijuana, chances are there’s something to the tales.

It could be, of course, that the marijuana rumors are part of a carefully contrived media manipulation, a product of the same strategy that’s seen him trading his sweet-faced choirboy look for that of an Odd Future gangbanger wannabe.

19 is an awkward age. Poor fashion choices, dubious companions, even full-fledged self-sabotage are predictable pitfalls for anyone at that point in life, multi-millionaire pop star or McDonald’s fry cook alike.

But while there’s no proof that the Beeb’s goofy, diva-like, and potentially career-destroying behavior of late are the product of a too-close acquaintance with the devil weed, when even your own manager is suggesting you go to rehab, chances are you’ve got a problem.

Next question, and it’s an obvious one: so what? There must a million 19-year-old potheads in North America. Does it matter if one of them happens to be richer and more famous than the rest of them put together?

If Bieber winds up wrecking his fabulously successful career, isn’t that what child stars typically do? If the gigs dry up and he has to resort to tell-all memoirs, Lifetime movies, or hawking reverse mortgages on late night TV, he’ll still get by.

“Oh my god!” I can hear you protesting, “It’s only pot. Don’t get carried away.”

Yeah, only pot. Why, in many states, it’s officially “medicine,” which must mean it’s good for you, right?

I started smoking pot when I was about Bieber’s age, and I once thought that, too. In fact for more than 20 years of my life I would have sworn that marijuana made me smarter, wiser, more moral, and probably even more handsome. In reality, as most people who knew me during that time will happily tell you, it made me an obnoxious dingbat.

That seems to be the effect it has on most of its users. The problem is—a big problem—is that the more stoned you get, the more likely you are to believe the complete opposite.

It’s only logical: why would people spend tons of money and (at least in some jurisdictions) even risk arrest to take a drug that made them look and act dumber than they already were? Unless, of course, one of the chief effects of the drug were to stand reality on its head and translate bleary-eyed dumbfoundedness into a half-assed approximation of cosmic insight and understanding?

Marijuana users hate it when you point out that the “high” they experience is a form of temporary derangement if not clinical insanity. What they’re even less likely to appreciate—or be aware of—is that the derangement isn’t necessarily temporary.

That’s not to say it’s permanent—serious long-term research needs to be done—but the mind-altering effects of marijuana last long after you stop toking down on the joints or bong hits. Days? Weeks? Months? How about years?

I’m not necessarily the ideal guinea pig, but that’s how long it took in my case: somewhere between three or four years before the inverted perceptions of my dope years felt fully restored to their former levels of functionality.

“But wait!” I can hear legions of dopers protest. “Just because you had a problem with marijuana doesn’t mean everybody else does. I mean, look at all the great art and philosophy that came out of the baby boom generation when they started smoking weed en masse in the 1960s!”

To which I can only respond: yeah, just look at it.

One of the most pernicious impacts of marijuana is the illusion that the universe revolves around the user, and that said user is uniquely qualified to understand and explain this to lesser mortals not under its influence. It’s not hard to see why this could be particularly problematic in the case of a 19 year old, who by dint of age and hormones alone, is already convinced he knows everything.

Add to the mix the fact that said teenager is one of the richest and most famous entertainers in the world, surrounded by yea-sayers willing, for the sake of inclusion in the magic circle, to tell him endlessly how brilliant he is. Should it be surprising when the young man has trouble keeping himself, shall we say, grounded?

Is this why the wheels seem to be coming off the well-oiled Bieber juggernaut? After years of scarcely putting a foot wrong, the boy wunderkind suddenly can’t seem to do anything right. As a former pothead myself, I can only say, “Been there, done that.”

Of course no one, let alone millions of kids, ever looked up to me as a role model the way countless teens and tweens to with the Beeb. Granted, he could argue that he never signed up for that when he set out to be a superstar. He’s perfectly entitled to make his life about nothing but, as Ice Cube memorably put it, “bitches and money.”

But before heading down that road, he might also want to take Dr. Dre’s advice under consideration, advice that, even if Dre later changed his tune, holds truer than ever today: